iOS: Remove background color for UIWindow and UIViewController's root view

They were handy while debugging the iOS platform plugin, but should not
affect users who link against debug libraries, so let's just remove them.

Change-Id: I61b157e81130e5d951c22892e00f71e593082b1d
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qiosapplicationdelegate.mm

@@ -60,10 +60,6 @@
     self.qiosViewController = [[[QIOSViewController alloc] init] autorelease];
     self.window.rootViewController = self.qiosViewController;
 
-#ifdef QT_DEBUG
-    self.window.backgroundColor = [UIColor cyanColor];
-#endif
-
     self.window.hidden = NO;
 
     return YES;

src/plugins/platforms/ios/qiosviewcontroller.mm

@@ -48,14 +48,6 @@
 
 @implementation QIOSViewController
 
-- (void)viewDidLoad
-{
-#ifdef QT_DEBUG
-    if (!self.nibName)
-        self.view.backgroundColor = [UIColor magentaColor];
-#endif
-}
-
 -(BOOL)shouldAutorotate
 {
     // Until a proper orientation and rotation API is in place, we always auto rotate.